A Vastly Increased Chemical Variety of RNA Modifications Containing a Thioacetal Structure

Recently discovered new chemical entities in RNA modifications have involved surprising functional groups that enlarge the chemical space of RNA. Using LC‐MS, we found over 100 signals of RNA constituents that contained a ribose moiety in tRNAs from E. coli. Feeding experiments with variegated stable isotope labeled compounds identified 37 compounds that are new structures of RNA modifications. One structure was elucidated by deuterium exchange and high‐resolution mass spectrometry. The structure of msms²i⁶A (2‐methylthiomethylenethio‐N6‐isopentenyl‐adenosine) was confirmed by methione‐D3 feeding experiments and by synthesis of the nucleobase. The msms²i⁶A contains a thioacetal, shown in vitro to be biosynthetically derived from ms²i⁶A by the radical‐SAM enzyme MiaB. This enzyme performs thiomethylation, forming ms²i⁶A from i⁶A in a first turnover. The new thioacetal is formed by a second turnover. Along with the pool of 36 new modifications, this work describes a new layer of RNA modification chemistry.     

Synthesis and Antimicrobial Activity of Some Condensed [4‐(2,4,6‐Trimethylphenyl)‐1(2H)‐oxo‐phthalazin‐2‐yl]acetic Acid Hydrazide

Some new 1,2,4‐triazolo‐, 1,3,4‐oxadiazolo‐, 1,3,4‐thiadiazol‐, and pyrazolo‐2,4,6‐trimethylphenyl‐1(2H)‐oxo‐phthalazine derivatives were synthesized and identified by IR, ¹H NMR, ¹³C NMR, MS and elemental analysis. The new compounds were synthesized with the objective of studying their antimicrobial activity.     

Synthesis and Antimicrobial Activity of 1,3,4‐Oxadiazole‐2(3H)‐thione and Azidomethanone Derivatives Based on Quinoline‐4‐carbohydrazide Derivatives

A new series compounds of quinoline derivatives were synthesized by reaction of 3‐(carboxymethyl)‐2‐arylquinoline‐4‐carboxylic acids 1a , 1b , 1c with different nucleophiles. The structures of the new compounds were elucidated on the basis of FTIR, ¹H‐NMR, ¹³C‐NMR spectral data, GC/MS, and chemical analysis. Investigation of antimicrobial activity of all new compounds was evaluated using a broth dilution technique in terms of minimal inhibitory concentration count against four pathogenic bacteria and two pathogenic fungi. Most of the new compounds were significantly active against bacteria and fungi.     

New Glycosidic Constituents of Abutilon pakistanicum

Pakisides A and B ( 1 and 2 , resp.), new catalpol‐type iridoid glycosides, and a new glycoside, 3 , of scutellarein have been isolated from the AcOEt‐soluble fraction of the whole plant of Abutilon pakistanicum, along with buddlejoside and lapachol. The structures of new compounds were elucidated by spectroscopic techniques including ¹H‐and ¹³C‐NMR (DEPT), and 2D‐NMR experiments.     

New Donor‐Functionalized Cp Ligands: Synthesis and Complexation Behaviour of Quinoxalyl and Benzothiadiazolyl Systems

Sodium cyclopentadienide reacts as nucleophile with 4,7‐dibromo‐2,1,3‐benzothiadiazole (BTZ) and leads to the new donor‐functionalized ligand Cp^BTZ. Related quinoxalyl Cp systems have been prepared using Pd‐catalyzed coupling with zincated Cp‐metal complexes. The new ligands comprise two N‐donor atoms; one of them is located in a distal position relative to the metal centre so that it cannotcoordinate in a chelating manner. With Cp^BTZ ligand derivatives severalmetal complexes have been synthesized. The new chromium(III) complex Cp^BTZCrCl₂ ( 12 ) becomes upon activation an active catalyst for the polymerization of ethylene. Relying on DFT calculations and analysis of spin‐density distribution combined with paramagnetic NMR data a chelating coordination of the Cp^BTZ ligand is feasible in 12 .     

The Pyridazine Scaffold as a Building Block for Energetic Materials: Synthesis,Characterization, and Properties

In the present studies, the synthesis of new energetic materials based on the pyridazine scaffold and their characterization is the main subject. For this purpose, desired 3,5‐dimethoxy‐4,6‐dinitropyridazine‐1‐oxide ( 7 ) was synthesized in the first instance. The persubstituted pyridazine precursor laid the groundwork for further preparative modification. The targeted functionalization through the regioselective introduction of various smaller amine nucleophiles such as methylamine or 2‐aminoethanol gave several new energetic materials. Among them are 3,5‐bis(methylamino)‐4,6‐dinitropyridazine‐1‐oxide ( 8 ), 3,5‐bis(methylnitramino)‐4,6‐dinitropyridazine‐1‐oxide ( 9 ), 3,5‐bis(dimethylamino)‐4,6‐dinitropyridazine‐1‐oxide ( 10 ), and 3,5‐bis((2‐hydroxyethyl)amino)‐4,6‐dinitropyridazine‐1‐oxide ( 11 ). With the aim of increasing the detonation performance, compound 8 was additionally nitrated and 3,5‐bis(methylnitramino)‐4,6‐dinitropyridazine‐1‐oxide ( 9 ) was obtained. These new energetic materials were characterized and identified by multinuclear NMR (¹H, ¹³C, ¹⁴N, ¹⁵N) and IR spectroscopy, elemental analysis and mass spectrometry. In addition, their sensitivities toward impact, friction and electrostatic discharge were thoroughly examined. Furthermore, obtained single‐crystals of the substances were characterized by low‐temperature single‐crystal X‐ray diffraction.     

Structure elucidation and NMR assignments of two new pyrrolidinyl quinoline alkaloids from chestnut honey

The complete ¹H, ¹³C and ¹⁵N NMR spectral assignments of two new alkaloids isolated from chestnut honey and structurally related to kynurenic acid have been made using 1‐D and 2‐D NMR techniques, including COSY, HMQC and HMBC experiments. The new compounds have been identified as 3‐(2′‐pyrrolidinyl)‐kynurenic acid and its γ‐lactam derivative. Copyright © 2009 John Wiley & Sons, Ltd.     

Syntheses,crystal structures,and metal ion complexation studies of novel diaza‐18‐crown‐6 ligands containing aromatic thiol‐derived side arms

The Mannich aminomethylation reaction of aromatic thiols has been used to produce diaza‐18‐crown‐6 ligands containing thiol‐derived side arms. Thiophenols were attached to the azacrown through N‐CH₂‐S linkages even in the presence of hydroxy or acetamido groups. Heteroaromatic thiols containing N=C‐SH (or NH‐C=S) structural fragments were attached to diaza‐18‐crown‐6 by N‐CH₂‐N linkages with the thiol becoming a thione function. X‐ray crystal structural analyses show the N‐CH₂‐S and N‐CH₂‐N linkages for some of the new macrocyclic compounds. Interactions of four of the new diaza‐18‐crown‐6 ligands with Na⁺, K⁺, Ba²⁺, Ag⁺, Zn²⁺, Cd²⁺, Ni²⁺, and Cu²⁺ were evaluated by calorimetric titration at 25° in methanol. The results show that these ligands form stable complexes with many of the metal ions studied.     

Cytotoxic Evaluation of Pungencine: A New Tropane Alkaloid from the Roots of Erythroxylum pungens O. E. Schulz

A new tropane alkaloid as well as a new substitution group, (3‐endo,8‐anti)‐8‐methyl‐8‐azabicyclo[3.2.1]oct‐3‐yl 4‐hydroxy‐3,5‐dimethoxybenzoate, called pungencine ( 1 ), was isolated from the roots of Erythroxylum pungens O. E. Schulz . The structure was elucidated by spectral analyses, including ¹H‐ and ¹³C‐NMR and 2D‐NMR techniques (¹H,¹H‐COSY, NOESY, DEPT, HMQC, and HMBC) and HR‐ESI‐MS. Furthermore, compound 1 was tested for cytotoxicity against several cell lines (Jurkat, HL‐60, U937, K562, KG‐1, and U266) and was determined not to inhibit cell viability at 10 μM .     

1,10‐Phenanthroline and Non‐Symmetrical 1,3,5‐Triazine Dipicolinamide‐Based Ligands For Group Actinide Extraction

The synthesis and evaluation of new extractants for spent nuclear fuel reprocessing are described. New bitopic ligands constituted of phenanthroline and 1,3,5‐triazine cores functionalized by picolinamide groups were designed. Synthetic routes were investigated and optimized to obtain twelve new polyaza‐heterocyclic ligands. In particular, an efficient and versatile methodology was developed to access non‐symmetric 2‐substituted‐4,6‐di(6‐picolin‐2‐yl)‐1,3,5‐triazines from the 1,3,5‐triazapentadiene precursor in the presence of anhydride reagents. Extraction studies showed the ability of both ligand series to extract and separate actinides selectively at different oxidation states (U^VI, Np^V,VI, Am^III, Cm^III, and Pu^IV) from an acidic solution (3 M HNO₃). Phenanthroline‐based ligands show the most promising efficiency for use in the group actinide extraction (GANEX) process due to a higher number of donor nitrogen atoms and a suitable pre‐organization of the dipicolinamide‐1,10‐phenanthroline architecture.     

Intercalation of Coordinatively Unsaturated FeIII Ion within Interpenetrated Metal–Organic Framework MOF‐5

Coordinatively unsaturated Fe^III metal sites were successfully incorporated into the iconic MOF‐5 framework. This new structure, Fe^III‐iMOF‐5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single‐crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid‐state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed Fe^III, whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the Fe^III ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate Zn^II within the MOF‐5 SBU. This new MOF structure displays the potential for metal‐site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials.     

Cyclotris(paraquat‐p‐phenylenes)

Reported here is the synthesis, solid‐state characterization, and redox properties of new triangular, threefold symmetric, viologen‐containing macrocycles. Cyclotris(paraquat‐p‐phenylene) ( CTPQT⁶⁺ ) and cyclotris(paraquat‐p‐1,4‐dimethoxyphenylene) ( MCTPQT⁶⁺ ) were prepared and their X‐ray single‐crystal (super)structures reveal intricate three‐dimensional packing. MCTPQT⁶⁺ results in nanometer‐sized channels, in contrast with its parent counterpart CTPQT⁶⁺ which crystallizes as a couple of polymorphs in the form of intercalated assemblies. In the solid state, MCTPQT^3(.+) exhibits stacks between the 1,4‐dimethoxyphenylene and bipyridinium radical cations, providing new opportunities for the manipulation and control of the recognition motif associated with viologen radical cations. These redox‐active cyclophanes demonstrate that geometry‐matching and weak intermolecular interactions are of paramount importance in dictating the formation of their intricate solid‐state superstructures.     

Microwave‐assisted synthesis of a novel phosphorus‐containing spiroorthoester,characterization and cationic polymerization

A new phosphorus‐containing spiroorthoester, (1,4,6‐trioxaspiro [4,4] nonan‐2‐yl)‐methyl 3‐[10‐(9,10‐dihydro‐9‐oxa‐9‐phosphaphenanthrene‐10‐oxide)]‐propanoate (SOE‐P), was synthesized under microwave irradiation with a short reaction time (1 h), because classical thermal heating did not lead to the desired product. The structure of the new monomer was confirmed by ¹H, ¹³C, and ³¹P. SOE‐P was homopolymerized and copolymerized with phenylglycidyl ether with ytterbium triflate as a cationic initiator in DSC experiments. These reactions were monitored by FTIR/ATR, and the formation of poly(ether‐ester)s with a pendant bulky phosphorylated group was shown. © 2006Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4722–4730, 2006     

Enhanced Performance of Benzothieno[3,2‐b]thiophene (BTT)‐Based Bottom‐Contact Thin‐Film Transistors

Three new benzothieno[3,2‐b]thiophene ( BTT ; 1 ) derivatives, which were end‐functionalized with phenyl ( BTT‐P ; 2 ), benzothiophenyl ( BTT‐BT ; 3 ), and benzothieno[3,2‐b]thiophenyl groups ( BBTT ; 4 ; dimer of 1 ), were synthesized and characterized in organic thin‐film transistors (OTFTs). A new and improved synthetic method for BTT s was developed, which enabled the efficient realization of new BTT ‐based semiconductors. The crystal structure of BBTT was determined by single‐crystal X‐ray diffraction. Within this family, BBTT , which had the largest conjugation of the BTT derivatives in this study, exhibited the highest p‐channel characteristic, with a carrier mobility as high as 0.22 cm² V^?1 s^?1 and a current on/off ratio of 1×10⁷, as well as good ambient stability for bottom‐contact/bottom‐gate OTFT devices. The device characteristics were correlated with the film morphologies and microstructures of the corresponding compounds.     

A New 3,5‐Bisporphyrinylpyridine Derivative as a Fluorescent Ratiometric Probe for Zinc Ions

A new 3,5‐disubstituted pyridine with two porphyrin moieties was prepared through an efficient synthetic approach involving 2‐formyl‐5,10,15,20‐tetraphenylporphyrin ( 1 ), piperidine, and catalytic amounts of [La(OTf)₃]. 3,5‐Bis(5,10,15,20‐tetraphenylporphyrin‐2‐ylmethyl)pyridine ( 2 ) was fully characterized and its sensing ability towards Zn²⁺, Cu²⁺, Hg²⁺, Cd²⁺, and Ag⁺ was evaluated in solution by absorption and fluorescence spectroscopy and in gas phase by using matrix‐assisted laser desorption/ionization (MALDI)‐TOF mass spectrometry. Strong changes in the ground and excited state were detected in the case of the soft metal ions Zn²⁺, Cd²⁺, Hg²⁺, and Cu²⁺. A three‐metal‐per‐ligand molar ratio was obtained in all cases and a significant ratiometric behavior was observed in the presence of Zn²⁺ with the appearance of a new band at 608 nm, which can be assigned to a metal‐to‐ligand charge transfer. The system was able to quantify 79 ppb of Zn²⁺ and the theoretical calculations are in accordance with the stoichiometry observed in solution. The gas‐phase sensorial ability of compound 2 towards all metal ions was confirmed by using MALDI‐TOF MS and in solid state by using polymeric films of polymethylmethacrylate (PMMA) doped with ligand 2 . The results showed that compound 2 can be analytically used to develop new colorimetric molecular devices that are able to discriminate between Hg²⁺ and Zn²⁺ in solid phase. The crystal structure of Zn^II complex of 3,5‐bisporphyrinylpyridine was unequivocally elucidated by using single‐crystal X‐ray diffraction studies.     

Triterpenoidal Secondary Metabolites from Lantana Camara Linn.

Three new pentacyclic triterpenoids, camarin ( 1 ), lantacin ( 2 ), and camarinin ( 3 ) were isolated from the aerial parts of Lantana camara Linn ., together with seven known compounds. The structures of the new constituents were elucidated by chemical transformation, HR‐EI mass spectrometry, and NMR spectroscopy, including 1D (¹H‐ and ¹³C‐NMR) and 2D (¹H,¹H‐COSY, NOESY, ¹H,¹H‐TOCSY, J‐resolved, HMQC, and HMBC) experiments.     

Synthesis and Characterization of Dendrimeric Bridged Salen/Saloph Complexes and Investigation of Their Magnetic and Thermal Behaviors

Eight new multinuclear Fe^III and Cr^III complexes involving the tetradentate Schiff bases N,N′‐bis(salicylidene)ethylenediamine (salenH₂) or N,N′‐bis(salicylidene)benzene‐1,2‐diamine (salophH₂) and the two new ligands 4,4′,4″,4′′′,4′′′′,4′′′″‐[1,3,5‐triazine‐2,4,6‐triyltris(nitrilomethylidyne‐4,1‐phenyleneoxy‐1,3,5‐triazine‐6,2,4‐triyldiimino)]hexakis[benzoic acid] ( 4 ) or 5,5′,5″,5′′′,5′′′′,5′′′″‐[1,3,5‐triazine‐2,4,6‐triyltris(nitrilomethylidyne‐4,1‐phenyleneoxy‐1,3,5‐triazine‐6,2,4‐triyldiimino)]hexakis[benzene‐1,3‐dicarboxylic acid] ( 5 ) were synthesized (Schemes 1 and 2) and characterized by means of ¹H‐NMR and FT‐IR spectroscopy, elemental analysis, LC/MS analysis, AAS (atomic‐absorption spectrum) analysis, thermal analyses, and magnetic‐susceptibility measurements. The complexes can also be characterized as low‐spin distorted‐octahedral Fe^III and Cr^III complexes bridged by carboxylato moieties.     

White‐Light Emission from Dual‐Way Photon Energy Conversion in a Dye‐Encapsulated Metal–Organic Framework

The design of white‐light phosphors is attractive in solid‐state lighting (SSL) and related fields. A new strategy in obtaining white light emission (WLE) from dual‐way photon energy conversion in a series of dye@MOF ( LIFM‐WZ‐6 ) systems is presented. Besides the traditional UV‐excited one‐photon absorption (OPA) pathway, white‐light modulation can also be gained from the combination of NIR‐excited green and red emissions of MOF backbone and encapsulated dyes via two‐photon absorption (TPA) pathway. As a result, down‐conversion OPA white light was obtained for RhB⁺@LIFM‐WZ‐6 (0.1 wt %), BR‐2⁺@LIFM‐WZ‐6 (2 wt %), and APFG⁺@LIFM‐WZ‐6 (0.1 wt %) samples under 365 nm excitation. RhB⁺@LIFM‐WZ‐6 (0.05 wt %), BR‐2⁺@LIFM‐WZ‐6 (1 wt %) and APFG⁺@LIFM‐WZ‐6 (0.05 wt %) exhibit up‐conversion TPA white light under the excitation of 800, 790, and 730 nm, respectively. This new WLE generation strategy combines different photon energy conversion mechanisms together.     

Poly(Taurine‐Glutathione)/Carbon Nanotube Modified Glassy Carbon Electrode as a New Levofloxacin Sensor

A new highly sensitive and selective electrochemical levofloxacin sensor based on co‐polymer‐carbon nanotube composite electrode was developed. Taurine and Glutathione were electrochemically co‐polymerized on multiwalled carbon nanotubes modified glassy carbon electrode (Poly(TAU‐GSH)/CNT/GCE) and used as a levofloxacin sensor in pH 6 phosphate buffer solution. The new composite electrode surfaces were characterized by scanning electron microscopy, atomic force microscopy and electrochemical impedance spectroscopy. Under the optimized conditions, two linear segments were obtained for increasing LEV concentrations between 20 nmol L^?1‐1 μmol L^?1 and 1.5 μmol L^?1‐55 μmol L^?1 LEV with a detection limit of 9 nmol L^?1 using amperometry. Poly(TAU‐GSH)/CNT/GCE exhibited high sensitivity, selectivity with good stability. The new sensor was employed for real samples of LEV tablets and urine. Promising results were obtained with good accuracy which were also in accordance with LC‐MS/MS analysis.     

Phlomisamide and Phlomisteriod: A New Ceramide and a New Stigmasterol Derivative from Phlomis cashmeriana

Phlomisamide ( 1 ), a new ceramide, and a new stigmasterol derivative, phlomisteriod ( 2 ), have been isolated from Phlomis cashmeriana. Their structures were elucidated by comprehensive analysis of their 1D‐ (¹H‐ and ¹³C‐NMR) and 2D‐NMR (COSY, HMQC, HMBC), and HR‐EI‐MS data.